Tag: fine-structure constant

In the early 1960s, Princeton physicist Robert Dicke invoked the anthropic principle to explain the age of the universe. He argued that this age must be compatible with the evolution of life, and, for that matter, with sentient, conscious beings who wonder about the age of the universe. In a universe that is too young for life to have evolved, there are no such beings. Over the decades, this argument has been extended to other parameters of the universe we observe around us, and thus to questions such as: Why is the mass of the electron 1,836.153 times smaller than that of the proton? Why are the electric charges of the up and down quarks exactly 2/3 and -1/3, respectively, on a scale in which the electron’s charge is -1? Why is Newton’s gravitational constant, G, equal to 6.67384 x 10-11? And, the question that has deeply puzzled so many physicists for a century (since its discovery in 1916): Why is the fine structure constant, which measures the strength of electromagnetic interactions, so tantalizingly close to 1/137 —the inverse of a prime number? (We now know it to far greater accuracy: about 1/137.035999.) Richard Feynman wrote: “It’s one of the greatest damn mysteries of physics: a magic number that comes to us with no understanding by man. You might say the ‘hand of God’ wrote that number, and ‘we don’t know how he pushed his pencil'” (QED: The Strange Theory of Light and Matter, page 131, Princeton, 1985). The great British astronomer Arthur Eddington (who in 1919 proved Einstein’s claim that spacetime curves around massive objects by making observations of starlight grazing the Sun during a total solar eclipse) built entire numerological theories around this number; and there is even a joke that the Austrian physicist and quantum pioneer Wolfgang Pauli, who throughout his life was equally obsessed with the number 137, asked God about it when he died (in fact: in a hospital room number 137) and went up to heaven; God handed him a thick packet and said: “Read my preprint, I explain it all here.” But if constants of nature are simply what they are, nothing more can be said about them, right?

Well, our viewpoint may suddenly change if a startling new finding should be confirmed through independent research by other scientists. Recently, astrophysicist John Webb of the University of New South Wales in Sydney, Australia, and colleagues published new findings that indicate that the fine structure constant may not be a constant after all—it may vary through space or time. Through observations of galaxies that lie 12 billion light-years roughly to the north with those at the same distance lying to the south, the team discovered variations in the fine structure constant amounting to about 1 part in 100,000. It is not clear whether quantum effects would drastically change when a fundamental constant such as the fine structure constant varies by such minute amounts. But if they do, and the change in the constant is significant, it could mean that there are universes—or distant parts of our own universe—where matter as we know it, and hence life, could not exist. Such a conclusion would greatly amplify the weight of the anthropic principle as a powerful argument for why we observe and measure the physical parameters we do. It is important to note that there is still skepticism about the finding, expressed for example in this post from Sean Carroll last year. But the possibility that this result is real cannot be discounted.